Field of the Disclosure
The present disclosure relates to an internal combustion engine, and more particularly to an internal combustion engine that, in accordance with an operating region, switches between a stoichiometric EGR mode in which the engine performs operation at the theoretical air-fuel ratio while executing recirculation by means of an EGR apparatus, and a lean mode in which the engine performs operation at an air-fuel ratio that is leaner in fuel than the theoretical air-fuel ratio without performing EGR by means of the EGR apparatus.
Background Art
An internal combustion engine equipped with a supercharger and a water-type intercooler is disclosed in JP 2005-233116 A that, in accordance with an operating region, switches between an NA lean mode in which lean-burn operation is performed utilizing intake air that is not turbocharged by the supercharger, a turbocharging lean mode that performs lean-burn operation utilizing turbocharged intake air having a high temperature, and a normal turbocharging mode that performs normal combustion operation in a turbocharging state. According to the technology disclosed in the aforementioned JP 2005-233116 A, in the NA lean mode all of the intake air is supplied to a bypass passage that bypasses the intercooler, in the turbocharging lean mode the intake air is shared between the intercooler and the bypass passage, and in the normal turbocharging mode all of the intake air is supplied to the intercooler.
An internal combustion engine equipped with a supercharger and a water-type intercooler is disclosed in JP 2008-255884 A which adjusts the flow rate of intake air that bypasses the intercooler in accordance with the load state of the internal combustion engine. According to the technology disclosed in the aforementioned JP 2008-255884 A, in a high-speed and high-load region the amount of cooling with respect to the intake air is reduced to raise the intake air temperature, and in a low or medium speed region or a low or medium load region, intake air is cooled by the intercooler to lower the intake air temperature.
As described above, technology is known that adjusts an intake air temperature according to the load state of an internal combustion engine.
Note that, in addition to the above described patent literature, JP 11-210477 A and JP 2003-239747 A and the like may be mentioned as examples of literature describing the state-of-the-art at the time of filing the present application.